class_docstr: Tree node of a dendrogram.
code: def groups(self, n):
      queue = [(self._value, self)]
  
      while len(queue) < n:
          priority, node = queue.pop()
          if not node._children:
              queue.push((priority, node))
              break
          for child in node._children:
              if child._children:
                  queue.append((child._value, child))
              else:
                  queue.append((0, child))
          # makes the earliest merges at the start, latest at the end
          queue.sort()
  
      groups = []
      for priority, node in queue:
          groups.append(node.leaves())
      return groups
  
imports: import copy
  from abc import abstractmethod
  from math import sqrt
  from sys import stdout
  from nltk.cluster.api import ClusterI
label_desc: Use image node_id 3 for calling the _DendrogramNode obj's underlying member method code with example usage: obj.groups(n) and returns: groups